The invention belongs to the field of energy modification and transmission, particularly to the transmission of solar energy from space to an earth location.
Apparatus for converting solar energy into other forms of energy such as laser and maser beams has been well developed. For example, by a multi-step process, an electrical current can be generated in a circuit containing photovoltaic or thermal converters, or both, exposed to sunlight, and this current can be applied to a laser to produce a narrow, intense beam of coherent (single frequency) light, sometimes referred to as a laser beam. In the microwave region, the corresponding device is called a maser, and the similar narrow intense beam of microwave energy is called a maser beam characterized by ability to penetrate clouds, smoke and haze, as demonstrated by radar equipment. Apparatus for converting laser beams into electrical energy and generating maser beams with the electricity is readily made by known techniques, and techniques for placing apparatus precisely in polar and equatorial orbits are likewise well known, as well as automatic and manual telemetry controls between the earth and satellites, and between satellites, for remote control of altitude, attitude, speed, direction of travel, pitch, yaw, and operation of various components.
Techniques are well developed for placing a satellite in stationary position relative to some selected earth area so as to place it in equatorial orbit at the same rotational speed as the earth and in the same direction. However, this poses a problem because the earth shadows it at night, stopping the collection and transmission of solar energy. To solve this problem, elaborate heat sink devices and battery systems have been proposed to store heat energy in the sunlight and release it at night, as shown for example in Hanold et al U.S. Pat. No. 3,029,596. Another possibility would be to utilize three satellites spaced at 120.degree. apart around the earth so that two would always be in the sunlight and could transmit to the one that happens to be in the earth's shadow at any particular time.
A still further problem in absorbing solar energy in space is the extremely high temperatures involved, requiring careful design to prevent the apparatus from being destroyed by the sun. Actual working temperatures of 2,100.degree. Kelvin have been proposed for solar energy concentrators in space. Receivers operating at such temperatures require special and complex designs to minimize their tendency at these very high temperatures to reradiate a substantial portion of the collected heat energy, thereby degrading the efficiency of the apparatus.